


Side Effects

by aliceecrivain



Series: The Start of Something New [2]
Category: Durarara!!
Genre: Alternate Universe - High School, Alternate Universe- No Supernatural, Established Relationship, Falling In Love, Fluff, Grinding, Hand Jobs, M/M, Making Out, Marking, No Plot/Plotless
Language: English
Status: Completed
Published: 2016-08-23
Updated: 2016-08-23
Packaged: 2018-08-10 12:22:38
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,663
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7844773
Author URL: https://archiveofourown.org/users/aliceecrivain/pseuds/aliceecrivain
Summary: <blockquote class="userstuff">
              <p>Shizuo was comforted by how hungrily Izaya kissed him sometimes. Izaya was good at hiding behind fake expressions and laughs and biting commentary, and it was hard to know what the hell he was feeling, if it was real, if it was a trick. It was at times like these, when he pushed and Izaya pushed back harder, that he felt the most secure in whatever this thing was between them.</p>
            </blockquote>





	Side Effects

**Author's Note:**

> OkAY allow me to explain. When I first wrote this, I imagined it within the Durarara!! School Musical universe, which is why it's a part of this series and also why I hadn't posted it before. (To be fair, you don't have to have read the main work to understand this one, but I think it does make more sense in context.) I was concerned about the content because the main work is rated T and also because this is, in the grand scheme of things, pretty pointless. Honestly, I just wanted to write them kissing and then this happened ¯\\_(ツ)_/¯
> 
> However, I've been told recently that some people might want to read it, so I decided to post it anyway, devil take the hindmost! Please do mind the rating on this one though, and keep in mind that it really is very plotless. I always imagined this taking place after the events of DSM, after their relationship was more developed, but it's up for interpretation ;)
> 
> But enough rambling. I hope you enjoy this extra tidbit, short as it is~

Shizuo was comforted by how hungrily Izaya kissed him sometimes. Izaya was good at hiding behind fake expressions and laughs and biting commentary, and it was hard to know what the hell he was feeling, if it was real, if it was a trick. Shizuo figured he probably shouldn’t think about it like that, but he also figured he didn’t have much of a choice. He’d rather feel mildly guilty about it now than like a total dumbass if it turned out to be true and he _hadn’t_ considered it.

But it was at times like this, when he pushed and Izaya pushed back harder, that he felt the most secure in whatever this thing was between them. As good as Izaya was with words, they communicated better physically most of the time, and Shizuo was okay with that. For all of Izaya’s talking, it seemed like he was just as bad at actually saying the shit that mattered as Shizuo was, and this was an agreeable alternative.

They were in Izaya’s house which was fucking terrifying, although the other had assured him his sisters were sleeping over at a friend’s house and that his parents were hardly ever home. Izaya shook his head at Shizuo’s paranoia, but closed to the door to appease him nonetheless. Shizuo didn’t argue. It gave him something to push Izaya up against.

He pulled back to gasp a breath, still not really used to doing this, not even really sure if he was doing it right, but Izaya had yet to object much. He was only permitted to stay away a few moments before the other boy leaned forward and caught his mouth again, slinging his arms up around Shizuo’s shoulders and hooking them behind his neck, pulling them closer together in the process. Izaya’s mouth was soft and warm, and Shizuo thought the way it felt against his own was becoming addictive.

Their noses bumped together when Izaya abruptly pulled back, but the two remained close enough together that Shizuo felt like they must be breathing the same air again and again and that was what was making him feel so damn lightheaded. Izaya’s cool fingers ran down along his arm, catching at his wrist and tugging at his hand where he’d planted it against the door when he’d captured Izaya in the first place. He frowned in confusion, but let Izaya take it.

“Your hands can be useful tools, Shizu-chan,” he commented airily. “I suggest you use them.” He proceeded to pull Shizuo’s hand down and set it against his waist, causing the tempo of Shizuo’s heartbeat to kick up a few notches. He could feel the quick rise and fall of the other’s breathing there, and the heat of his skin through his thin shirt. Shizuo thought that sometimes Izaya had good ideas.

He kissed Izaya again before he could say something else mildly condescending, catching at the corner of his mouth first before he reached his real target. He slid his other hand down from the door as well so they were a matching set, holding onto Izaya. There was something about holding him like this, feeling him tangible and solid in front of him, his body moving, arching more and more sharply against him, that made this whole thing feel more real.

Slowly he ran circles around the sharp tops of Izaya’s hipbones with his thumbs, just testing it out. He’d never touched anyone like this before. Izaya laughed into his mouth, the sound buzzing against their connected lips, and curled his fingers into Shizuo’s hair. He also opened his own mouth in the process, granting Shizuo’s tongue access before either of them really expected it. Shizuo pulled back immediately, but couldn’t move far due to his hold at Izaya’s waist which he didn’t feel like relinquishing any time soon and the other’s grip on his hair. “Sorry.”

Izaya frowned at him. “For what?”

Shizuo felt his face heat, the embarrassment hotter and less nice than the warmth building in his cheeks before had been. “I didn’t mean to just—”

“Shizu-chan,” Izaya interrupted him for which Shizuo was vaguely grateful, even if it was with that annoying nickname. “If you’re going to make-out with me, your tongue is probably going to go in my mouth. In fact, if your tongue doesn’t go in my mouth you’re probably doing it wrong.”

Shizuo’s grip tightened instinctively and he felt hot down to his neck at how blunt Izaya was being while also making him feel like he was being talked to like a child. “Shut the fuck up. I was trying to be considerate.”

“Well, stop,” Izaya suggested, an annoyingly self-satisfied smirk stretching across his face.

Shizuo all but bit it off.

He felt Izaya take a deep breath with his nose and felt the fingers in his hair tighten and pull more than they had before. They were quiet for a while then and Shizuo was reminded that that was one of his favorite things about kissing Izaya. They fell into an easy sort of rhythm and Shizuo decided he wanted to actually do something with his hands as Izaya had suggested.

He slid them up and down his sides a couple of times, remarking on how damn skinny the other boy was before one ventured up Izaya’s back, running up along his spine, out along to the vague outline of his shoulder blades and then back down to his lower back. Izaya made a small satisfied noise at Shizuo’s explorations which caused Shizuo to pull him closer, since his hand’s new resting spot gave him good leverage. Izaya all but fell into him and the space between them collapsed abruptly, making it so their chests were pressed together.

Shizuo gasped at the feeling of Izaya’s body flush up against his own like this and Izaya took the opportunity to dip his tongue past Shizuo’s lips and _he_ didn’t pull back even when Shizuo tensed momentarily. It felt kind of weird, but Shizuo kept his mouth open, letting Izaya deepen the kiss for the time being and focusing more on the way Izaya’s hands were moving along his shoulders and down his back, mindlessly touching in a way that brought back the nice warmth from earlier tenfold.

Shizuo moved his hand up to Izaya’s jaw, tracing the bone to his neck where he found a new hold. When Izaya swallowed he could feel his Adam’s apple move and he ran his thumb up along the line of his throat in response. Izaya chose that moment to pull back to breathe raggedly which worked well for Shizuo because the pale curve of Izaya’s neck was becoming too much for him to resist. He ducked down to kiss under his chin and back down the path his thumb had just traced.

Izaya whined quietly at the action and tilted his head back to grant Shizuo easier access, baring his neck willingly, letting his head rest back against the door behind him. Shizuo felt a thrill go through him at the lack of resistance he was met with and kissed his way up behind Izaya’s ear, which he seemed to like judging by the way his hands scrambled for purchase on Shizuo’s shirt. He moved on then to his temple and his forehead and his flushed cheeks and was going for his nose when Izaya turned away, huffing in frustration. “Stop it,” he ordered. “Just _kiss_ me already.”

Shizuo laughed, pressing his forehead against Izaya’s, taking in the way the other boy’s chest heaved against his. “I was.”

“Not like that,” Izaya said, his voice darkened by heat. “I’m not three. I’m not your estranged aunt at a family reunion. If you’re going to kiss me, then _kiss me_. I’d hope even you could—”

For once, Shizuo was happy to oblige, tilting his head and licking into Izaya’s mouth, swallowing whatever else he was going to say. Izaya tugged harder at his hair in retaliation, but he didn’t really mind, especially considering Izaya’s tongue was flicking out to meet his a few seconds later. He was getting more used to kissing like this and he decided he liked it. He ran his tongue along the edge of Izaya’s gums and ran his hands back down his sides.

He felt Izaya shudder against him and felt something desperate and raw well up within his chest. Without really registering what he was doing, he ran his hands lower, down and under Izaya’s thighs, and hoisted him up, pushing him hard back against the door and bearing his weight entirely. Shizuo broke off to bite at his neck, feeling Izaya cling hard to his shoulders. The other made a noise of surprise and managed to say about half of his name before he broke off into an honest-to-god moan. More than anything Shizuo wanted to make him make that sound again and again and _again_.

He backed off to lick at the wound he’d created, feeling slightly guilty when Izaya brought a hand up to feel at it. The heat and the rush of the moment had gone to his head, and he hadn’t really been thinking. Hell, he still wasn’t. He was discovering just how much he wanted Izaya—he’d thought about it, yeah, but it was a lot clearer with him there, in his arms, flushed and breathing hard and making those little sounds—and more than anything he wanted to kiss him everywhere and never stop.

But then he brought his eyes up to meet Izaya’s and he didn’t see irritation or fear, just blown out pupils and that familiar sly glint in his eyes, and there was something _pleased_ about his expression that Shizuo hadn’t been expecting. A lazy smile spilled across Izaya’s face and he’d never looked more like himself. Silly words like _beautiful_ and _want_ were still pinging around Shizuo’s head when Izaya slung his arms around his shoulders, relaxing in his hold, and leaned forward, catching at Shizuo’s lower lip with his teeth, tugging slightly on it before moving on. He dragged his lips up the side of Shizuo’s jaw and Shizuo felt his eyes flutter closed against his will. Pretty soon, he could feel Izaya’s warm breath against his ear.

“Shizuo,” he murmured and the other shivered at the use of his full name. “We should move.”

Shizuo opened his eyes and followed Izaya’s gaze over to the bed sitting innocuously in the corner. He swallowed hard, feeling nerves freeze his limbs. Slowly, he set Izaya down. As much as his body was aching to go further, he didn’t want to rush into this. Izaya must have noticed—hell, when didn’t he notice?—because his smile turned appeasing and he pressed his hands against Shizuo’s chest while he regained his balance, a little unsteady on his feet still. “Relax. I’m not going to ruin Shizu-chan’s innocence quite yet. I just want to sit down.”

Shizuo scowled at him, shaking his head. “Who’s innocent now?”

There was something sultry about Izaya’s laugh and it made Shizuo want to push him right back up against the door. “I guess you’re right. I didn’t think you’d give me a hickey so soon. I should return the favor. Then we could match.”

Shizuo felt himself blanch slightly thinking of what his friends, or worse, his family, would say if they saw, but Izaya waved him off. “I’m only kidding.” He moved then, sliding out of Shizuo’s reach and moving toward the bed, beckoning Shizuo after him. He resisted momentarily, but soon followed as if there was some physical sort of pull between them that would only let them be so far apart. Izaya stood next to the plainly decorated bed with his arms crossed over his chest. When Shizuo approached, he pointed. “Sit.”

“I’m not a dog,” Shizuo grumbled.

Izaya smiled sweetly. “Fine. Sit, please.”

He hardly thought the statement was any more sincere than the first, but he did as he was told because already he was missing the feeling of Izaya’s warmth in his arms. Shizuo sat down, feeling the bed decompress underneath him and scooting back further at Izaya’s behest. The situation was surreal. He never thought he’d be sitting here on Izaya’s bed of all places. He was still caught up in trying to process it when he felt a heavy weight plop down in his lap and looked up to see Izaya climbing on top of him. Heat flushed his face immediately and he tried to back up only to find the wall behind him. Izaya flashed him a dangerous grin and set his hands down on Shizuo’s shoulders.

He settled down further onto Shizuo, and Shizuo tried not to focus too much on what was going on below his waist. At least Izaya was mostly just on his legs. Unfortunately the key word there was “mostly.”

“This is better, isn’t it?” Izaya asked, sounding pleased with himself again. Shizuo swallowed hard. “You can touch me again now.”

Shizuo brain had stopped functioning properly at that point, which was probably all for the better, but it did mean that stupid shit like, “Where?” was slipping out of his mouth. His voice sounded rough and foreign to him.

Izaya leaned in, nosing at his cheek lightly. “Don’t ask questions you don’t want to hear the answers to.”

“Who doesn’t want to hear the answers...?” Shizuo demanded, turning his head to bump lightly against Izaya’s.

Izaya’s laugh was breathless and Shizuo closed his eyes so he could only hear his voice and feel his breath. “Ask again.”

“ _Izaya_.”

He made no move to answer, only nipped down Shizuo’s jaw, humming tunelessly.

Shizuo huffed, figuring they were both out of it enough that playing along wouldn’t be held over him for too long later. “Where can I touch you?”

He could feel Izaya’s teeth right next to his mouth. “Anywhere you want.”

Shizuo shook his head in incredulity at the other’s shamelessness, but quickly turned to catch at his mouth to do something about the ache in his chest that throbbed at the other’s words. Izaya kissed back eagerly and Shizuo dropped his hands back to his waist. The permission he’d been granted was kind of overwhelming and besides, he liked holding him there. It was becoming a new sort of familiar he thought he could get used to. Their mouths moved together again until Shizuo noticed that Izaya’s shirt had dipped down some to reveal his collarbone and became distracted.

He detached his lips from Izaya’s, moving back to kiss him quickly a couple more times because he couldn’t resist, before he began kissing along the new space revealed to him. Izaya giggled and dug hands into Shizuo’s hair again, pulling at and parting it. “I can see your roots from here, Shizu-chan,” he teased, rubbing at Shizuo’s scalp with his thumbs. “You’re lucky you’re so tall or you’d have to dye it more often.”

Shizuo nipped harder at his collarbone in an attempt to shut him up, and it mostly worked. Izaya leaned closer to him, pushing out his chest mindlessly. Shizuo paused in his ministrations to nuzzle under the other’s chin and breathe in his scent. He’d never tell him, because he figured all he’d get would be a string of animal-related insults, but he really liked the way Izaya smelled.

“Are you sniffing me?” Izaya asked with uncanny timing.

“No,” Shizuo said, probably too quickly. “I have to _breathe_ you know.”

Izaya snickered. “That’s not breathing. _I’m_ breathing. _You’re_ doing this.” He paused to bury his nose in Shizuo’s hair and inhale, which wasn’t really fair, Shizuo thought, because it was completely distracting. When he spoke again, Shizuo could feel his lips against his forehead. “And you say you’re not a dog.”

Shizuo frowned. So much for not telling him. “If I’m a dog, what’s that make you?”

The other’s grin stretched wider. “I think Shizu-chan’s getting smarter.”

Shizuo decided he wanted to do something to get the other boy to stop talking again, and he noticed his hands still resting on Izaya’s hips. He dragged them down onto his thighs instead which were resting flush on either side of Shizuo’s as he kneeled on top of him. Shizuo could feel the lean muscle under the give of the skin there, belying Izaya’s strength where it wasn’t usually visible simply from looking at him, small and skinny as he appeared. Izaya turned to rest his cheek on top of Shizuo’s head meanwhile, and sighed, which was a start. Shizuo’s hands curved around his thighs, massaging the softer skin there, working it in his hands, his thumbs even daring occasionally to run along the insides where it was warmer and softer yet.

Izaya made another little noise when he did, so he repeated the action more frequently, moving so his palms dipped down into the space between where their legs touched as well. More and more small sounds came from Izaya’s throat and Shizuo felt himself responding without meaning to, especially when Izaya started rubbing at his shoulders. Finally he reached back up to catch at Izaya’s mouth again, having stayed away for too long already and wanting to see if he’d make more of those noises into his mouth.

He did, and Shizuo kissed him harder for it, dropping his jaw open wider to deepen the kiss.

Izaya’s hands drifted down in between his own arms to Shizuo’s waist meanwhile, pulling at the hem of his shirt. Before he knew it, Shizuo could feel hands on his stomach and sliding up his sides, Izaya having slipped them underneath the article of clothing. He jolted slightly in surprise, but Izaya tracked his mouth easily, ending the separation almost immediately and not offering the slightest justification or apology for what he was doing. Shizuo did think, however, that he could feel him smiling again.

The contact of Izaya’s hands on his bare skin made him feel breathless, like he couldn’t suck in enough air no matter what he did, and the warmth he’d been feeling unfurling through his body before began to turn hot. Izaya’s fingers curled at his sides before he began moving them, tracing up along Shizuo’s chest and back. Shizuo was surprised at how big of a difference one less layer of fabric made in the intensity of everything he was feeling. He thought he was doing less kissing and more just sort of mouthing at Izaya at that point, only reaching his target about half the time.

Izaya’s palms brushed over his nipples, and Shizuo choked for a second at the flash of sensation. The other practically purred against his lips and did it again, rubbing with the heels of his palms and Shizuo let out a small groan that didn’t sound like any other noise he’d made in his life. He rubbed harder at Izaya’s thighs, becoming more thoughtless about where he was touching, dipping down and around occasionally to rub at his lower back because it made Izaya arch further into him. Izaya’s tone twisted into something more needy when he ran that path so sometimes he dared to go even lower, down below his tailbone, which made Izaya’s hips twitch.

They were mostly breathing into each other’s mouths then, neither of them having enough focus to kiss properly so Shizuo returned to his mouth’s second favorite place, Izaya’s neck, kneading the skin there with his lips and, occasionally, his teeth. Izaya gasped and Shizuo could make out his name on the other’s lips: “ _Shizuo_.”

In hindsight, Shizuo didn’t think Izaya really meant to do it, at least at first. Probably because he was so caught up in the moment, in the almost electric charge between them built up by their movements, that he responded in what could have been considered a pretty damn encouraging way.

Regardless of whose fault it was, Izaya shifted suddenly in Shizuo’s lap, moving much closer from where he’d been fairly stationary before, and Shizuo instinctively pushed his hips up at the movement and the friction it created. Izaya’s breath hitched momentarily, but then he moved again, rolling his hips more purposefully against Shizuo who muttered an emphatic, “Fuck,” at the sensation.

Shizuo didn’t really know how to deal with how incredible that felt or how badly he wanted more. He did know that the ache that had been in his chest before had dropped down somewhere much lower and that if the friction stopped he’d probably go crazy, so he gripped harder at Izaya’s thighs and repeated his earlier movement, pleased when Izaya did the same.

Then the two of them were truly grinding against each other, pushing back and forth in tandem, too caught up in the heat of the moment to notice much what they were doing. Shizuo had a brief moment of anxious clarity when he realized that Izaya could feel very clearly how much this had been turning him on before he noticed Izaya was really no better off at the moment. He kept his mouth on Izaya’s neck and thought he could probably keep doing this forever, if Izaya would let him. He’d never felt anything like this. The weight and heat of Izaya’s body against his was so different and new and suddenly he thought he might have a problem on his hands because he couldn’t imagine it not like this. How’d he ever gotten off before anyway? At the moment he couldn’t remember.

To both of their surprise, it was Izaya who suddenly broke the spell, freezing where he was and pulling back. “Wait,” he said, breathless. “We should stop.”

Shizuo could think of a hundred reasons why that was the worst goddamn idea he’d ever heard in his life, but the look in Izaya’s eyes made him fall silent momentarily until all he could come up with was a simple, “Why?”

Izaya looked at him like he was crazy. He brought his hand down between Shizuo’s legs so suddenly that he hissed through his teeth at the touch. Fortunately, or unfortunately, Shizuo wasn’t really sure anymore, he pulled back soon after. “Shizu-chan, you were nervous about me giving you a hickey.” In another context it might have sounded condescending, and maybe it was meant to, but Izaya was too breathless for the inflection to come off that way. In fact, in this situation, it sounded a hell of a lot like he actually cared which was pretty damn rare, considering his track record.

Shizuo supposed he had a point, but still, what the hell were they gonna do now? Take turns in the shower? Shizuo himself was achingly hard if he was being honest and he doubted Izaya was better off. Even sitting like this now with Izaya just out of reach, having extracted his hands entirely, was painful. “I’m...okay,” he said before he could think about it too much, then realized that might not be all there was too it. “Do you not want to?”

He looked Izaya over. His lips were swollen, his hair and clothes disheveled. His chest was still moving heavily as he caught his breath. Shizuo could see the marks he’d made on Izaya’s neck, some still wet, and the somewhat glassy look in his eyes and a surprisingly strong feeling of possessiveness washed over him. Izaya bit at his lip, glancing away slightly before he shook his head.

Shizuo reached up to cup at Izaya’s face, drawing him back so he could kiss him, more softly than before. “I don’t want to stop.”

“Me neither,” Izaya whispered, and that was all Shizuo needed to hear.

He kissed him more rapaciously than before, and Izaya moved back into Shizuo’s lap proper. He didn’t slip his hands back under Shizuo’s shirt though. Instead, he dropped them back down and started working to get their pants open. Shizuo moved to protest, but Izaya shook his head. “I’m not going to come in my pants like I’m back in sixth grade, Shizuo.”

Shizuo worried briefly about how willing he was becoming to agree with the other and let Izaya go back to his task. He tried to bite back a groan and failed when Izaya’s fingers closed on his cock and exposed him to the open air. He didn’t even try when Izaya did the same for himself and pressed their cocks together, gripping them both in his hand. “Shit, Izaya.”

Izaya chuckled darkly. “Mhm.” He didn’t give much warning before he started stroking excruciatingly slow. Shizuo was already sensitive and the fact that it was Izaya doing this told him that he wasn’t going to last long. Their breathing grew quick and heavy again, and Izaya tipped his forehead to press against Shizuo’s, meeting his eyes purposefully. “Shizuo.” He moved his hand to take hold of Shizuo’s again, bringing it to meet his other one, his tone turning urgent. “Come on. Your hands are bigger than mine.” 

Shizuo thought he was probably shaking, but he complied, letting his hand replace Izaya’s and watching as Izaya’s mouth fell open in a silent groan when he did. There was something about touching Izaya like this and watching how it made him react that made the muscles in Shizuo’s abdomen coil tightly. Then he started to move his hand.

He started off slow, trying, with what little focus he had left to sketch out the shape of Izaya, to burn the way it felt to have him hard in his hand like this into his memory. Pretty soon though, he couldn’t help but speed up, tightening his grip as he jerked both of them off. Izaya kept twitching his hips forward in little sporadic thrusts like he couldn’t help himself and it made his cock slide against Shizuo’s in a way that made Shizuo’s heart skip a beat each time and made him all the more aware of the edge he was steadily approaching. It didn’t help that Izaya was looking down so intently, watching the whole time, his lips parted unconsciously, like he couldn’t drag his gaze away.

Shizuo was right. Neither of them lasted long. Izaya started holding onto his shoulders too tightly soon after Shizuo began, and the edges of Shizuo’s vision started to go a few minutes later. Izaya came first, gasping and shuddering against him, his cock flushing hot in his hand, curling up and making it hard for Shizuo to keep his grip, as he followed soon after, feeling all the tension in his body finally release and hardly noticing how sticky his hand had become. Shizuo pulled away because it was becoming too much to keep touching, even if the half-offended, half-sated noises Izaya kept making when he continued stroking after he should have stopped were nice to listen to. Izaya slumped against him completely without any mind for his own body weight. Shizuo didn’t really mind.

He didn’t notice what Izaya was doing at first, just felt him kissing along his neck and well, that was nice, no wonder Izaya had liked it so much. Soon after though, he registered the sharp of teeth and the pressure of suction and Izaya’s smug smile against his jaw. “There. Much better.”

Shizuo thought to ask him about it but his mind was full of static and he didn’t really want to move, even to speak at the moment. He was just happy to have Izaya up against him, warm and real. Besides, Izaya was connecting their lips again soon after and that was distraction enough.

Shizuo _did_ notice the mark later, but not until after he’d gone home. He hated that he couldn’t even get too angry about it since he’d done about triple what he had to deal with now to Izaya. Apparently this was going to be one of the side effects of Izaya actually showing his affection, and well, if so, Shizuo thought he could probably learn to deal with that.


End file.
